The subjects of this study are: (a) 72 hyperactive adults 22 to 29 years of age who were diagnosed as hyperactive fifteen years previously and who have not been treated with methylphenidate; (b) 25 hyperactive adults 17 to 22 years of age who were diagnosed as hyperactive ten years previously and who have been treated with stimulant drugs (methylphenidate) for a period of at least three years; (c) 65 control subjects who will be matched with the above two groups with respect to age, I.Q. (WAIS), socioeconomic class, and sex. Forty-five of these control subjects were obtained several years ago at the time of the five year follow-up study. All hyperactive and control subjects will be assessed with respect to: (1) Psychiatric status: comprehensive history; psychiatric interview, a self rating scale of psychopathology; the SADS(L) (Schedule for Affective Disorders and Schizophrenia); (2) Drug Abuse (and non-medical drug use and alcohol use); (3) Antisocial Behaviour (including court referrals, and a detailed stealing history); (4) The California Psychological Inventory; (5) Tests of Self Esteem; (6) Tests of Social Skills; (7) Work Record (competence at work, number and types of jobs, and an employer's rating scale); (8) Car and Motorcycle Accidents; (9) School Guidance Questionnaire (methylphenidate-treated group only); (10) Attitudes to professional help and/or medication received (hyperactives only) (11) Physiological Measures: height, weight, blood pressure, resting pulse, electroencephalogram. This study will give us a clear picture of the final adult outcome of hyperactive children who were not treated with methylphenidate, and give us information on the efficacy and safety of stimulant therapy.